https://biblioteca.ugb.edu.sv/cgi-bin/koha/opac-search.pl?q=ccl=an%3A4306%20and%20au%3ARam%C3%83%C2%ADrez%20Molina%2C%20Julio%20C%C3%83%C2%A9sar%20and%20au%3ARivera%20Garciaguirres%2C%20Jos%C3%83%C2%A9%20Roberto&format=rss2 Search results for 'an:4306 and au:Ramírez Molina, Julio César and au:Rivera Garciaguirres, José Roberto' at Biblioteca UGB 0 20